I am 13 years old. I am 5ft 2 and 7st. How can I lose weight quickly before I go back to school in about a month. My parents won't let me diet as they keep going on that I am not fat even though I am. Because I live in England I have the problem of rain! Please help. How can I exercise to lose weight quickly? Oh and I can't use diet pills because again my parents won't let me.